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Proof Mooted For Heisenberg's Uncertainty Principle

Posted by Soulskill on from the he's-the-one-who-knocks dept.

ananyo writes "Encapsulating the strangeness of quantum mechanics is a single mathematical expression. According to every undergraduate physics textbook, the uncertainty principle states that it is impossible to simultaneously know the exact position and momentum of a subatomic particle — the more precisely one knows the particle's position at a given moment, the less precisely one can know the value of its momentum. But the original version of the principle, put forward by physicist Werner Heisenberg in 1927, couches quantum indeterminism in a different way — as a fundamental limit to how well a detector can measure quantum properties. Heisenberg offered no direct proof for this version of his principle. Now researchers say they have such a proof. (Pre-print available at the arXiv.) If they're right, it would put the measurement aspect of the uncertainty principle on solid ground — something that researchers had started to question — but it would also suggest that quantum-encrypted messages can be transmitted securely."

6 of 158 comments (clear)

  1. Fixed the summary by angel'o'sphere · · Score: 1, Informative

    ... the uncertainty principle states that it is impossible to simultaneously know^H^H^H^H measure the exact position and momentum of a subatomic particle the more precisely one knows the particle's position at a given moment, the less precisely one can know the value of its momentum.

    Fix.

    --
    Cost free eBook I read (by iBook/Kobo/Amazon/ObookO/Gutenberg etc.): "The Green Odyssey" by Philip Jose Farmer.
    1. Re:Fixed the summary by Prune · · Score: 3, Informative

      It's not just a practical issue for measurement, so your "fix" is invalid. The correct explanation is in this post: http://science.slashdot.org/comments.pl?sid=3904863&cid=44110125

      --
      "Politicians and diapers must be changed often, and for the same reason."
    2. Re:Fixed the summary by Anonymous Coward · · Score: 2, Informative

      Indeed. I don't know what crap "undergraduate textbooks" people use near the north pole, but here down under, the principle of Heisenberg is taught using _math_.

      It has always been about measuring (not "knowing", the universe doesn't give a damn about what you know or don't know or it would forbid god from existing. Instead, it just hampers aquiring new knowledge of the full state vector ;p). And it has always been a nice mathematical, strictly quantified trade off between the precision you'll get out of one of the measurements being inversely correlated to the precision you'll get out of the other measurement because the product of the two must be at least half the reduced plank constant.

  2. Re: You keep using that word... by Anonymous Coward · · Score: 2, Informative

    I too found the title odd

    [moot]
    - adjective
    1. open to discussion or debate
    2. of little practical value

  3. Re: You keep using that word... by mrvan · · Score: 4, Informative

    http://dictionary.reference.com/browse/moot says:

    verb (used with object)
    4. to present or introduce (any point, subject, project, etc.) for discussion.
    5. to reduce or remove the practical significance of; make purely theoretical or academic.

    So meaning 4 seems appropriate. Strange that a word simultaneously means to introduce it and to remove it from consideration, but it is a pretty old word I think so it has probably evolved quite a bit.

    Origin:
    before 900; Middle English mot ( e ) meeting, assembly, Old English gemt; cognate with Old Norse mt, Dutch gemoet meeting. See meet1

  4. Re:Uncertaintiy principle and Foruier Transforms by Anonymous Coward · · Score: 2, Informative

    He means the location of the sonic event. If you think of sound as particulate (a series of events a la granular synthesis) then the frequency of each event and the location in time of each event satisfy a sort of uncertainty principle. It's because the FFT of sine * normal curve is sine * normal curve, but the width of the normal curve is conjugate in each case (the limiting case is sine * delta -> sine * 1). This width represents the "certainty" that the actual frequency or location in time is at the center point. It's a neat trick but it's not clear how or if it relates to QM, except via the mathematical equivalence. Once you start asking "what, then is h?" or "how does scalar amplitude relate to quantum phase" the illusion of relevance kind of vanishes.